DESCRIPTION: Fanconi anemia (FA) homozygotes have an increased cancer predisposition. In addition to the extraordinarily high frequency of AML in FA patients (actuarial risk of 52 percent for the development of MDS and/or AML by 40 years of age), FA patients exhibit malignancies of a variety of organ systems, most commonly gastrointestinal and gynecologic. The high incidence of nonhematologic malignancy in FA patients is especially striking because of the predicted early death from hematologic causes associated with the syndrome. Thus patients are unusually young when they develop cancer, and the incidence of malignancy probably would be considerably higher if patients had a longer life expectancy. There is evidence that heterozygote carriers of homozygous recessive familial cancer syndromes, such as Fanconi anemia, ataxia telangiectasia and xeroderma pigmentosum, are at increased risk for cancer. It is now possible to ascertain the carrier status by means of molecular tests rather than impute carrier status through probabilities, and thus it may be possible to arrive at a definitive answer to the role of heterozygosity among Fanconi anemia carriers. This study will directly address the etiology of cancer that involves the role of Fanconi anemia heterozygosity. The major aim of this retrospective cohort study will be to evaluate whether FA heterozygotes are at increased risk for developing cancer. In order to address this aim this study will use the extensive resources of the International Fanconi Anemia Registry at Rockefeller University. The sample will consist of 758 Fanconi anemia heterozygote grandparents of FA probands and 758 grandparents who do not carry an FA allele. Risk factor information will be obtained by questionnaire, blood will be collected for DNA analysis, and diagnostic pathology information will be collected using a systematic approach. Analyses will be undertaken to evaluate the role of Fanconi anemia heterozygosity for cancer. If carriers are found to be at increased risk, this information can be used to target individuals for cancer prevention strategies.